This invention relates to a frame structure for housing electronic equipment, and, more particularly, to an earthquake resistant support frame for electronic equipment.
Electronic equipment, which may be mainframe computers, information technology equipment, telecommunications circuitry, air traffic control systems, or similar equipment, generally comprises sophisticated and delicate components assembled in a manner such that the electrical and mechanical connections therebetween are delicate and subject to interruption of the continuous flow of electronic data as a result of the loss of the connection. Continuous flow of electronic data through the electronic equipment is often of critical importance to a system and can lead to detrimental results in the event of an interruption of that flow. Frame retention systems that form an integral part of electronic equipment systems are designed to ensure the continuous flow of data and are utilized to curtail the likelihood of damage to electronic equipment that may result from either man-made or natural vibratory motion.
The vibratory forces generated by an earthquake or other seismic shock activity can often be of a sufficient magnitude to break the physical connections between the electrical and mechanical components. Various degrees of protection can be afforded to electronic equipment in order to prevent or limit the amount of damage that can potentially result from seismic activity. Frame retention systems in the form of aseismic support structures and methods of securement have been developed and are used within the electronics industry to compensate for the vibrations resulting from this seismic activity.
In order to prevent the interruption of the flow of data, the electronic equipment should be installed and secured in such a manner so as to withstand or resist the vibratory forces that may detrimentally affect the connections. It is a normal practice within the electronic industry, as known from the prior art, to contain the electronic equipment within a frame-like structure and secure the structure to a base, which is usually fixedly secured to the floor. The frame-like structure, as well as the base, is usually modular; however, the sections involved are typically of massive size and weight to accommodate the large vibratory forces generated by earthquakes. While this method is straightforward and effective, the structures involved, viz., the frame itself as well as the base, are often costly to manufacture and do not lend themselves to being conveniently moved to the site of installation. Moreover, this method fails to address the problem of relocation of the equipment.
Another method of preventing interruption of data flow is through the use of less rigid structures that allow the frame to flexibly shift under the vibratory forces generated by earthquakes. In particular, one approach is to mount casters on an underside of the frame to allow the frame free access to movement over a surface. Normally, the casters can be braked such that the frame is prevented from movement during normal use. If vibratory forces of a sufficient and predetermined magnitude are sensed and experienced by the frame, the caster braking system can be released so that the movement of the frame absorbs the energy of the earthquake. The use of casters as support members, however, contributes to the instability of the frame as vibratory forces are experienced. In the event of a significant earthquake, the vibrations generated may be sufficient to cause the frame to tip over.
An electronic equipment frame having an integrated earthquake restraint system is needed that is of a manageable size and weight. The inventive frame is a flexible structure being adjustable vertically with respect to a level plane of a flooring surface to accommodate electronic equipment of heights variable between 36 units EIA and 42 units EIA loaded at up to 35 pounds per unit EIA. The structure may be modified to accommodate electronic equipment of heights that are greater than 42 units EIA. An optional brace, when properly secured, renders the frame capable of withstanding a higher NEBS rating and, in one embodiment of the invention, an NEBS GRE-63 Zone 4 earthquake rating. Without the brace, the frame is capable of withstanding NEBS GRE Zone 1 and Zone 2 earthquake ratings. Furthermore, the inventive frame is mountable to either a raised or a non-raised flooring surface using a leveler and tie down system that ensures a uniform height over a level area of the frame, induces a pre-stress load over the flooring surface, and provides adequate insulation and vibrational attenuation to the electronic components. The floor mounting plate is easily accessible to allow the frame to be easily moved.
An earthquake resistant frame structure has a base member, a plurality of support members extending normally from the base member, a top portion disposed over the end portions of the support members, a extension member disposed over the top portion, side stiffeners positioned perpendicularly between the support members, and tie down assembly system positioned between the base member and a flooring surface. The extension member has a platform section and at least two legs depending substantially perpendicularly therefrom that slidingly engage the support members. The two legs have slots or holes therethrough configured to receive fasteners that, when secured to the support members, secure and maintain the extension member in position.
First and second panels protrude laterally from the frame structure to form an extension area, from which a bracket hingedly depends. The bracket, which is generally triangular in shape, is removably attached to the first panel. Removal of the bracket can be prevented by the installation of a locking hinge assembly. The locking hinge assembly is an L-shaped hinge having a first end pivotally received on the first panel and secured thereto. A second end of the L-shaped hinge is fixedly attached to the bracket. A variety of pin arrangements are used to prevent the removal of the bracket from the L-shaped hinge. The edge of the bracket that is distal from the hinged edge is securable to the second panel using a plate and bolt assembly.
The extension member includes a platform section and a plurality of legs depending from the platform section. Each leg includes openings therein that are engageble with corresponding openings in the frame structure. The extension member is securable to the frame structure by the insertion of fasteners extending through the openings in the legs and into the corresponding openings in the frame structure. Typically, the fasteners are bolts that are received through the openings in the legs and are threaded into the corresponding openings in the frame structure.
The tie down system includes at least one floor plate positionable between the frame structure and the flooring surface. A fastener extends through the frame structure, through the floor plate, and into the flooring surface. A leveling element is positioned between the floor plate and the flooring surface to level the frame structure, and insulators are positioned between the fastener and the leveling element to damp vibration.
The above-described inventive frame also enables an electronic system to be shipped fully populated. Casters are rollably fixed to the bottom of the frame, thereby allowing the frame to be easily rolled during shipment onto and off of a transport device and rolled to its final delivery location. Installation of the frame using the leveling elements, which are threaded such that the frame can be raised and lowered by articulating the leveling elements, allows the casters to remain secured to the bottom of the frame after the frame is mounted to the floor plates.